Abstract: In order to obtain the best purification conditions of total flavonoids from corncob extracted by ultrasonic-assisted deep eutectic solvent and determine the activity of purified flavonoids,the macroporous resins were screened and the purification process was optimized. The antioxidant activity of corncob flavonoids before and after purification was evaluated by the removing ability of 1,1-diphenyl-2-trinitrophenylhydrazine radical （DPPH） and 2,2-diazo-bis （3-ethyl-benzothiazole-6-sulfonic acid） diammonium salt radical （ABTS）. In addition,the antibacterial activity of flavonoids was determined by inhibiting the growth of Escherichia coli, Staphylococcus aureus and Bacillus subtilis in vitro. An experiment was used to determine hypoglycemic activity through the inhibition of α- amylase activity. The results showed that XAD-2 macroporous resin was suitable for purifying corncob flavonoids. The best conditions were the concentration of 1.00 mg/mL and pH of 4.0,the adsorption was carried out at a loading flow rate of 15 mL/h. After the adsorption was completed, the resin was eluted with 70 mL of 70% ethanol at a flow rate of 60 mL/h. Under this condition, the corncob flavonoids could be purified 2.65 times. Flavonoids from corncob had a stronger cleaning ability for DPPH· and ABTS· stronger after purification, but weaker than VC. The antibacterial activity of purified flavonoids was enhanced, and the order of antibacterial intensity was Staphylococcus aureus > Escherichia coli > Bacillus subtilis. The flavonoids of corncob showed hypoglycemic activity, and the hypoglycemic ability of its purified product was equivalent to acarbose. It could be seen that the corncob flavonoids extracted by ultrasonic assisted deep eutectic solvent had antioxidant, antibacterial and hypoglycemic activities, and XAD-2 macroporous resin was better in purifying flavonoids from corncob.

Key words: corncob, flavonoids, macroporous resin, antioxidant, antibacterial, hypoglycemic